Though premature deaths across the United States have reached a 20-year low, the gap between the healthiest and unhealthiest counties is still wide, according to a new report.

Though premature deaths across the United States have reached a 20-year low, the gap between the healthiest and unhealthiest counties is still wide, a report released Wednesday found.

Residents in the nation’s least healthy counties are twice as likely to die before age 75 as those who live in the healthiest counties, according to the 2013 County Health Rankings published by the Robert Wood Johnson Foundation (RWJF) and the University of Wisconsin Population Health Institute.

Researchers averaged data points from the five most and least healthy counties in each state to identify nationwide trends. They found that in the least healthy places, there was an average of 10,862 years of life lost to premature death per 100,000 residents (approximately ten fewer years per person) compared to 5,122 in the healthiest counties. The national average was 7,727 -- the lowest rate in 20 years, according to researchers.

The counties with the highest premature death rates had on average worse health behaviors and are poorer and less educated than their healthier peers.

“There’s a growing gap between those that are doing well and those that aren't,” says Michelle Larkin, public health team director at RWJF. “It does raise a lot of points about where people can make a difference to stem these trends.”

Those in the least healthy counties, compared to those in the healthiest, smoked more (24 percent versus 16 percent); reported more physical inactivity (32 percent versus 27 percent); were more obese (30 percent versus 23 percent); and had less access to primary-care doctors (a ratio of one doctor for every 2,129 residents versus one for every 1,491). They also had less access to recreational facilities: 3.8 facilities per 100,000 residents versus 11.3 facilities per 100,000 in the healthiest counties.

Beyond the more obvious health metrics, though, there was also a strong connection between socioeconomic factors and relative health. The unhealthiest counties had more than twice the number of children living in poverty (32 percent versus 15 percent in the healthiest counties). They were less educated (48 percent had some college versus 68 percent). They had significantly more single-parent households (37 percent versus 23 percent).

“The socioeconomic factors, like income and education, they are really key to understanding what's going on,” says Bridget Catlin, who oversaw the rankings’ compilation and analysis at the University of Wisconsin. “All of the factors that we include, they have all been shown to have a strong relationship with our health outcomes. More education does lead to better health. You can say that in general terms.”

There were a few data points that didn’t correlate as one might expect. There was no significant difference between the healthiest and unhealthiest counties when it came to access to healthy foods, the prevalence of fast-food restaurants or exposure to fine particulate matter, which is often emitted from power plants and automobiles.

Researchers say they hope their findings will encourage community activists and local officials to think beyond the obvious health measures and recognize that the health of their population also depends on the strength of their public education system and the vibrancy of their economy. Coinciding with the rankings’ release, RWJF and the Institute announced the winners of the 2013 Roadmaps to Health Prize.

Those winners have taken the rankings and turned them into action, Larkin says, which was the motivation to start compiling them in the first place.

“We're not looking for that silver bullet. We want people to say, ‘I'm a local business leader, a policymaker, what can I do?’” she says. “It’s about really shifting the conversation to one around civic engagement and how you can play a role, hold policymakers accountable for the decisions they make and leverage resources to tackle these really challenging problems.”

For a full explanation of the rankings' methodology, visit the website.